Twenty or thirty years ago, people generally had one or two points of contact, a home phone number and maybe a business phone number. Unless a person moved or changed jobs, these numbers were unlikely to change, and the numbers were often recorded by hand in a paper contact phone book or a ROLODEX.
Nowadays, however, the landscape has dramatically changed. With the onset of email, people often have a multitude of “addresses” at which they can be contacted.
Further, the prevalence of cellular phones has added an additional wrinkle. Users may buy new phones, without changing physical addresses, and change numbers. Additionally, since cellular phones store phone numbers, many people have stopped remembering phone numbers of friends and family. Of course, if a cellular phone is lost or ruined, all these stored numbers (and/or email addresses) may be lost.
Cellular phone stores may offer an option to have a list of numbers on an existing phone printed or backed up. But this requires a trip to the store to have this service performed. Even if the backup capability is available on a home-PC, through a wired connection, the user may have to remember to connect the phone and activate the back-up program.